Locking device for skip stitch mechanisms

ABSTRACT

A skipstitch mechanism for household sewing machines is disclosed in which a clutch device is provided for interrupting the needle bar reciprocation so that stitches may be skipped to form extremely long stitches as for basting or the like. The skipstitching is effected by the operation of the zigzagstitching mechanism of the sewing machine in one position of adjustment of the zigzag control means. A locking device is disclosed for holding the zigzag control means in position to effect skipstitching while the needle bar reciprocation is interrupted by the skipstitch means.

United States Patent 72] Inventor Stephen J. Illes Summit, NJ.

[21] Appl. No. 848,177 [22] Filed Aug. 7, 1969 [45] Patented Feb. 2, 1971 [73] Assignee The Singer Company New York, NY.

a corporation of New Jersey [54] LOCKING DEVICE FOR SKIP STITCH MECHANISMS 3 Claims, 6 Drawing Figs. [52] 0.5. CI. 112/158 [51] Int. Cl D05b 3/02 [50] Field ofSearch 112/158, 73, 109, 111

[5 6] References Cited UNITED STATES PATENTS 3,433,190 3/1969 Sagi Primary Examiner-Richard J. Scanlan, Jr.

Attorneys-Marshall J. Breen, Chester A. Williams, Jr. and

Robert E. Smith ABSTRACT: A skipstitch mechanism for household sewing machines is disclosed in which a clutch device is provided for interrupting the needle bar reciprocation so that stitches may be skipped to form extremely long stitches as for basting or the like. The skipstitching is effected by the operation of the zigzag-stitching mechanism of the sewing machine in one position of adjustment of the zigzag control means. A locking device is disclosed for holding the zigzag control means in position to effect skipstitching while the needle bar reciprocation is interrupted by the skipstitch means.

PATENT ED FEB 2 :97:

SHEET 1 [1F 2 INVENTOR Stephen J.Illes ATTORNEY PATENTED FEB 2 1971 SHEET 2 BF 2 INVENTOR. Stephen J. Illes ATTORNEY 1 LOCKING DEVICE FOR SKIP STITCH MECHANISMS BACKGROUND OF THE INVENTION This invention relates to skipstitch mechanisms for household sewing machines, and more particularly to a locking device for holding the zigzag control means in a position to effect skipstitching during interruption of the needle bar reciprocation by the skipstitch means. The U.S. Pat. application No. 848,175 of Edward J. Tullman discloses a skipstitch mechanism for a zigzag sewing machine in which the locking means for the zigzag stitching control of this invention may readily be applied. Reference may be had to the aforementioned patent application for the details of construction of the skipstitch mechanism. The skipping of stitches in a sewing machine may be accomplished by interrupting the needle bar reciprocation during continued operation of the other mechanisms of the sewing machine, such as the work feeding mechanism, so that long stitches are formed. Interruption of the needle bar reciprocation is accomplished by the operation of a clutch device which separates the needle carrying bar from the means by which it is ordinarily driven. In the skipstitch mechanism of the aforementioned U.S. Pat. application No. 848,175 of Edward J. Tullman the engagement and disengagement of the clutch device for separating the needle bar from its driving means is accomplished intentionally by a cam device which is operated by the actuating mechanism of the sewing machine so as to effect separation and reengagement of the clutch device substantially at the top of the stroke of needle bar reciprocation. If the clutching or declutching of the needle bar drive were to be occasioned at another portion of the stroke of the needle bar, the clutch device would be shifted relatively to the operating abutments therefor and relatively to the safety cam means therefor, so that considerable wear of the parts or possibly damage to these parts may be occasioned. Since the operation of the skipstitch mechanism of this invention can occur only in a certain predetermined setting of the zigzag control means of the sewing machine, this invention provides for a locking .device which operates to prevent the zigzag control means from being shifted out of a position for accommodating skipstitch operation while the needle bar drive is interrupted during skipstitching.

SUMMARY OF THE INVENTION The aforementioned objects and advantages of this invention are attained by the provision in a zigzag sewing machine of a skipstitch mechanism operative to interrupt the needle bar reciprocation during skipstitching together with a locking device which is provided for detaining the zigzag-stitching controls of the sewing machine in a position in which skipstitching is possible while the needle bar occupies an interrupted relation with its drive mechanism. This locking device protects the needle bar interrupting mechanism from damage or abnormal wear which might occur if the controls were to be shifted to terminate interruption of the needle reciprocation or to effect interruption of needle reciprocation at times other than the top of the needle bar stroke.

DESCRIPTION OF THE DRAWINGS With the above and additional objects and advantages in view, as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawing of a preferred embodiment in which:

FIG. 1 represents a perspective view of the skipstitch mechanism of this invention including only portions of the salient mechanisms of a sewing machine and illustrating the needle bar held in the elevated skipstitch position;

FIG. 2 is a front elevational view of the sewing head portion of a sewing-machine having the needle bar reciprocation interrupting means of this invention applied thereto and illustrating the manner in which the safety cam means deflects the needle bar in the event that the needle bar is inadvertently not detained in elevated position;

FIG. 3 is a front elevational view of a portion of the needle bar reciprocation interrupting means of FIG. 1 showing the latch means on the needle bar disengaged from the needle bar reciprocating drive means and interengaged with the keeper for retaining the needle bar substantially at the top of its stroke;

FIG. 4 is a left side elevational view of the spring biased latch lever of the needle bar reciprocation interrupting means of FIG. 3;

FIG. 5 is a top plan view of a sewing machine with a portion of the top cover plate removed showing the skipstitch mechanism of this invention applied thereto but with the sewing machine parts in a position for sewing; and

FIG. 6 is a cross-sectional view taken substantially along line 6-6 of FIG. 5 showing the parts during skipstitching and illustrating the means for locking the bight adjustment in maximum position during skipstitching.

The present invention may be applied to any sewing machine equipped with a needle-jogging mechanism for zigzag sewing. The accompanying drawings illustrate this invention applied to a sewing machine of the type illustrated in more detail in the copending U.S. Pat. application of Marsh et al., Ser. No. 827,867, filed May 26, 1969, to which reference may be had.

As shown in the drawings, the sewing machine has a frame including a bracket arm 11 formed with a sewing head 12. Joumaled in the bracket arm is a main drive shaft 13 which may be driven by an electric motor (not shown). A worm 14 on the main drive shaft meshes with a worm wheel 15 on a cam shaft 16 in the bracket arm to impart driving movement to a stack of pattern cams 17 on the cam shaft. Included on the top of the cam stack 17 is an exchangeable pattern cam 18 having a handle 19 which may be grasped by the operator in exchanging the pattern cam.

Journaled for swinging movement in the sewing head 12 on a vertical pin 21 is a needle bar gate 22 supporting a spherical bearing 23 for an endwise reciprocatory needle bar 24 carrying a needle 25 at its lower extremity. A second spherical bearing 26 for the needle bar is constrained in the sewing head 12 so that in addition to endwise reciprocation the needle bar can be jogged laterally as for the formation of zigzag stitches. For imparting endwise reciprocation to the needle bar, the main drive shaft 13 carries a counterbalanced crank 27 connected to a needle bar drive link 28 which embraces a stud 29 which is sustained on the needle bar by a block 30 provided with cheek pieces 31. The block 30 is not secured directly to the needle bar, but instead is freely slidable lengthwise thereon. Above the block 30 a collar 32 is securely fastened to the needle bar by a set screw 33. Pivotted to the collar 32 by a shoulder screw 34 is a latch lever 35 having an upstanding finger 36 and a depending arm 37. The depending arm 37 is formed with a lateral latch finger 38 shown in FIG. 1 adapted to engage beneath a latch notch 39 formed in the cheek piece 31 of the block 30 so as to secure the block 30 and the collar 32 together and thus complete an endwise reciprocatory needle bar driving connection between the needle bar 24 and the drive link 28. A coil spring 40 shown in FIG. 4 engages the latch lever 35 and the collar 32 and biases the latch finger 38 toward operative engagement with the latch notch 39 in the cheek piece 31.

A sheet metal angle bracket 41 is constrained on the collar 32 by the shoulder screw 34 and by an inturned limb 42 which extends alongside the collar 32. The angle bracket 41 is fonned with an inturned abutment stop 43 disposed in the path of motion of the latch lever 35. It is the function of the abutment stop 43 to prevent the latch finger 38 from being shifted into a position excessively near the needle bar. The abutment stop 43 will prevent the latch finger 38 from being turned beyond a point in which the inclined upper edge 44 of the cheek piece 31 can contact and urge the latch finger 38 outwardly and about the cheek piece and into cooperation with the latch notch 39.

For stabilizing the needle bar 24 when the block 30 is engaged with the collar 32, the collar 32 is formed with a depending projection 45 which fits snuggly between the cheek pieces 31 on the block 30.

Lateral jogging motion is imparted to the needle bar as for zigzag sewing by means of a zigzag drive link 50 which is pivotally connected to the needle bar gate 22 and has an integrating plate 51 pivoted thereon at 52 remote from the needle bar gate and adjacent to the cam stack. A spring 53 anchored in the bracket arm urges the drive link 50 and the integrating plate 51 toward the cam stack. Two pattern cam followers 54 and 55 are interposed between the integrating plate 51 and the cam stack, each pattern cam follower being slidably pivoted on a respective stud 56,57 in the bracket arm. For each cam follower a cam selecting mechanism is provided. FIG. illustrates at 60 a cam selecting mechanism for the front cam follower 54. The cam selector mechanism 60 comprises a lever system slidably joumaled on a rod 61 arranged transversely of the bracket arm and having an operator influenced knob 62 secured on an exposed arm 63 of the lever system. Axial motion of the lever system by depression of the knob 62 serves by way of axial shift of a lever arm 64 to engage a tail portion 65 of the front cam follower 54 to shift the pattern cam follower 54 out of engagement with the cam stack.

Turning of the lever system about the rod 61 serves by way of a link 66 to shift the follower along its support stud 56 into tracking relation with a selected pattern cam on the cam shaft 16.

A similar cam selecting mechanism is provided for the rear pattern cam follower so that the followers may be placed in tracking relation with any desired pattern cam in the stack and at least the front follower 54 may be placed in tracking relation with an exchangeable cam 18 atop the cam stack.

The stack of cams 17 and the exchangeable cam 18 constitute selectable response-producing records each having peripheral cam tracks'of which the radius can vary within predetermined limits and when tracked by one or both of the followers 54,55 serve to jog the needle bar for the production of zigzag stitches.

Pivoted on the cam shaft 16 beneath the stack of cams 17 is a bight control lever 70 having an operator influenced handle 71 thereon. Pivotally connected to the bight control lever 70 as by spherically headed stud 72 is the drive link 50 of the needle-jogging mechanism. By this connection with the bight control lever, the integrating plate 51 may be shifted laterally relatively to the two cam followers 54 and 55. When the bight adjusting lever handle 71 is positioned in the setting corresponding to maximum bight or width of zigzag stitching as illustrated in FIG. 5, the centerline of the pivotal connection 52 of the integrating plate is placed directly opposite to the front follower 54 which cancels out all influence of the rear cam follower 55 on the integrating plate. It is in this position of adjustment of sewing machine controls that the skipstitch mechanism of this invention can be operative.

Referring to FIGS. 1, 2 and 3 in which the needle bar mechanism is shown in detail, 80 represents a bracket which is supported within the sewing head 12, as is conventional in this type of sewing machine for supporting adjusting mechanism, such as dial (not shown) or the like for adjusting the downward spring pressure which is applied to a presser bar 82, slidable in the sewing head 12 and carrying at its lower extremity a conventional presser foot 83. The bracket 80 may be formed with a sloping abutment surface 84 which is positioned for engagement with the upstanding finger 36 of the latch lever 35 at the upstroke of the needle bar reciprocation whenever the needle bar is jogged laterally beyond that lateral position which exceeds its capability to form a stitch. The abutment surface 84 may also be formed on a separate plate secured to the bracket 80, or secured directly to the sewing machine frame. With reference to FIG. 1, it will be noted that the presser foot 83 is formed with a laterally elongated opening 86 for needle penetration. This presser foot needle aperture 86 conventionally corresponds in width with a needle aperture (not shown) formed in a throat plate 87 on which work is supported on the sewing machine. The needle apertures are formed sufficiently wide to accommodate the widest bight for lateral jogging movement which the needle is capable of making commensurate with the ability of the sewing instrumentalities to make a stitch. If the needle bar were to be jogged a greater distance laterally than is provided by the presser foot aperture 86, the needle would, of course, strike the presser foot and damage to the parts would result. When the term lateral jogging beyond a rangein which stitches are capable of being formed" is used in this specification, however, it will include not only limitations imposed by the width dimension of the needle aperture in the presser foot or throat plate, but will include also any limitations in the capability of the needle and loop taker to cooperate in the formation of stitches. The abutment surface 84 is so positioned on the bracket as to engage the upstanding finger 36 and shift the latch lever 35 so as to disengage the latch finger 38 from the latch notch 39 whenever, for any reason, the needle bar is jogged beyond that point in which it is capable of forming a stitch. Since the abutment surface 84 is disposed on the lefthand side of the collar 31 as viewed in FIGS. 1, 2, and 3, it will be apparent that disengagement of the latch lever 35 will be effected only when the needle bar is jogged in a direction to shift the needle to the right as viewed in FIGS. 1 and 2. It will be understood, however, that the abutment surface 84 may be placed at the opposite side of the needle bar and the latch lever 35 may be reversed so as to disengage the needle bar when it is jogged beyond a stitching range in the opposite direction.

For influencing separation of the drive for endwise reciprocation of the needle bar to cause skipped stitches with this invention a special response-producing record preferably in the form of a pattern cam may be inserted atop the cam stack 17 in place of a pattern cam which is capable only of influencing patterns of zigzag stitches. Such a pattern cam for skipstitching is illustrated at 90 in FIGS. 1, 5, and 6, and is characterized by peripheral cam surfaces 91 which are formed at a smaller radius than the smallest radius portions of any of the zigzag pattern cams in the stack 17. The skipstitching cam 90 is also formed with peripheral portions 92 which are disposed at a radius as large as that of the cam track portions of the zigzag pattern cams in the zigzag pattern cam stack 17. When the bight control handle 71 is shifted to the position of maximum bight as illustrated in FIG. 5 and a skipstitch cam 90 is positioned on the cam stack with the front follower 54 selected to track the skipstitch cam 90, those portions 91 of the skipstitch cam which are of smaller radial dimension than the smallest radius of any zigzag cam will shift the needle bar beyond the range of positions in which it is capable of forming'stitches, and on the succeeding upstroke of the needle the upstanding finger 36 of the latch lever 35 will strike the abutment surface 84 and separate the connection between the drive link 28 and the needle bar 24.

A resilient stop lug is secured by a screw 101 to the sewing head 12 in the path of reciprocation of the needle bar so as to prevent the needle bar from flying upwardly in a uncontrolled manner when the drive connection thereto is disengaged during high speed operation of the machine.

Secured as by a fastening screw 111 to the presser regulating bracket 80 is a retaining bracket 110. An inturned shoulder portion 112 of the retaining bracket is arranged in the path of the latch finger 38 of the latch lever 35 when the latch lever is forced out of operative engagement with the cheeks 31 of the block 30 as illustrated in FIG. 1. The shoulder portion 112, thus by engaging the latch lever 35, maintains the needle bar in elevated position while the block 30 slides downwardly relatively to the needle bar. Depending from the shoulder portion 112 of the retaining bracket and in the path of movement of the latch finger 38 of the latch lever 35 is an inclined cam ann portion 113 of the retaining bracket 110 which functions as is illustrated in FIG. 2 to urge the latch lever 35 and the needle bar 24 to the right as viewed in FIG. 2 in the event that the retaining shoulder portion 112 of the bracket 110 should accidentally fail to retain the needle bar in an elevated position during a skipstitch. Preferably, the inclined cam arm 113 of the retaining bracket should be adjusted very accurately so as to urge the needle bar sufficiently to prevent the needle from striking the edge of the presser foot or from striking the work support of the sewing machine and to this end an abutment stud 114 may be provided threaded into the inclined cam arm portion 113 of the retaining bracket 110 and adapted to engage the sewing head 12. The abutment stud is provided with a nut 115 which may be adjusted so as to position the retaining bracket very accurately relatively to the sewing head.

It will be appreciated that the abutment surface 84 and the retaining bracket 110 may be supported other than by the presser foot pressure regulator bracket 80 and, for instance, may be attached directly to the sewing head portion 12 of the sewing machine frame. By being carried on the bracket 80, however, the abutment surface 84 and retaining bracket 110 may be provided as a subassembly thereto facilitating manufacture of the sewing machine.

When the mechanism of this invention is effective to cause stitches to be skipped, it is preferable for the needle bar reciprocating means to be reengaged only while the needle bar driving link 28 and the collar 32 occupy positions at the upper extent of a stroke because then the latch finger 38 of the latch lever simply drops into engagement with the notch 39 beneath the cheek piece 31 and the incline 44 of the cheek piece 31 is not called upon to brush the latch lever to one side. As a result, considerably less wear is encountered and the risk of damage to the parts is lessened.

Since, as is conventional in sewing machine construction, the needle-jogging influence of the cam 90 on the cam shaft of the sewing machine will occur when the needle-driving link occupies a position in each cycle of operation corresponding to the elevated position of the needle, it is advantageous for the cam 90 to control reengagement of the needle-reciprocating means. Conversely, it would be detrimental for the operator to shift the bight control handle 71 out of maximum bight position during the skipstitch mode of machine operation. To lock the bight adjusting control lever 70 in maximum bight position 'during skipstitch a slabbed projection 130 is arranged depending from the needle bar jogging drive link 50 beneath the integrating plate 51 as illustrated in FIG. 6. Secured by screws 131 to the bracket arm 11 beneath the drive link 50 is a locking bar 132 formed with a notch 133. The locking bar 132 is positioned so that the notch 133 will be located opposite the slabbed projection 130 in the maximum bight position of the bight control lever 70. When the cam 90 provides for abnormal jogging of the needle bar beyond that in which stitches can be formed, the projection 130 will enter the notch 133 locking the bight control lever in the position of maximum bight while the needle bar remains in the skipstitch mode.

In FIG. 1 is illustrated a stitched material 120 to which long stitches are being applied using the skipstitch cam 90 illustrated in FIGS. 1, 5, and 6. This skipstitch cam 90 is formed with two diametrically spaced large diameter cam track portions 92, each portion occupying only one arm shaft revolution of the sewing machine in engagement with cam follower 54. All other cam track portions 91 of the skipstitch cam 90 are of small diameter and influence the skipstitch mode so that with a conventional drive ratio of 24 stitches for each rotation of the cam shaft 16, the cam will cause the needle bar reciprocating mechanism to partake of 11 cycles of motion with the needle bar disengaged for each cycle of motion with the needle bar operatively connected and exceedingly long stitches as illustrated in FIG. 1 will result. If the stitch length of the conventional sewing machine work feed is set, for instance, at approximately one-eighth of an inch per stitch, the stitches illustrated in FIG. 1 will be spaced by approximately 1% of an inch and such stitches will be useful as basting stitches. Other configurations of skipstitch cams 90 may be used, for instance, to produce conventional zigzag stitches during one portion of a cam shaft rotation and skipstitch during another portion thereof so as to provide for spaced groups of zigzag stitches.

Furthermore, this invention is not limited to the use of a pattern cam for producing jogging motion of the needle beyond the range in which stitching can be accomplished and during which the skipped stitches willbe provided. Any desired control for effecting such abnormal lateral jogging movement may be used as, for instance, a manual instrumentality whereby skipstitch may be caused to be formed at will simply by effecting an abnormal jogged position of the needle bar.

I claim:

1. A skipstitch mechanism in a sewing machine having a frame, actuating mechanism carried in said frame, a needle bar carried by said frame for endwise reciprocation and for lateral jogging movement for the formation of stitches, means driven by said actuating mechanism for imparting endwise reciprocation to said needle bar, mechanism driven by said actuating mechanism for imparting lateral jogging movement to said needle bar including a manually influenced zigzag control regulator, and interrupting means for said needle bar reciprocating means effective only during lateral jogging movement of said needle bar in a predeterminedposition of said manually influenced zigzag control regulator, interengaging locking means on said zigzag control regulator and on said sewing machine frame for preventing movement of said zigzag control regulator out of said predetermined position for influencing skipstitching during interruption of said needle bar reciprocating means.

2. A skipstitch mechanism as set forth in claim 1 in which said zigzag control regulator comprises a bight control regulator for regulating the length of zigzag stitching and in which the means for interrupting said needle bar reciprocation comprises mechanism for jogging the needle bar laterally beyond a predetermined range of laterally jogged positions in which it is possible for stitches to be formed, and in which said interengaging locking means is effective to detain said bight control regulator in a position corresponding to maximum width of zigzag during lateral jogging movement of said needle bar beyond said predetermined range of positions.

3. A skipstitch mechanism as set forth in claim 2 in which said needle bar is provided with a needle jogging drive link formed with a projection, a bar; carried by said sewing machine frame and arranged transversely of said drive link, said transverse bar being formed with a latch notch accommodating said drive link projection during interruption of said needle bar reciprocation. 

1. A skipstitch mechanism in a sewing machine having a frame, actuating mechanism carried in said frame, a needle bar carried by said frame for endwise reciprocation and for lateral jogging movement for the formation of stitches, means driven by said actuating mechanism for imparting endwise reciprocation to said needle bar, mechanism driven by said actuating mechanism for imparting lateral jogging movement to said needle bar including a manually influenced zigzag control regulator, and interrupting means for said needle bar reciprocating means effective only during lateral jogging movement of said needle bar in a predetermined position of said manually influenced zigzag control regulator, interengaging locking means on said zigzag control regulator and on said sewing machine frame for preventing movement of said zigzag control regulator out of said predetermined position for influencing skipstitching during interruption of said needle bar reciprocating means.
 2. A skipstitch mechanism as set forth in claim 1 in which said zigzag control regulator comprises a bight control regulator for regulating the length of zigzag stitching and in which the means for interrupting said needle bar reciprocation compRises mechanism for jogging the needle bar laterally beyond a predetermined range of laterally jogged positions in which it is possible for stitches to be formed, and in which said interengaging locking means is effective to detain said bight control regulator in a position corresponding to maximum width of zigzag during lateral jogging movement of said needle bar beyond said predetermined range of positions.
 3. A skipstitch mechanism as set forth in claim 2 in which said needle bar is provided with a needle jogging drive link formed with a projection, a bar carried by said sewing machine frame and arranged transversely of said drive link, said transverse bar being formed with a latch notch accommodating said drive link projection during interruption of said needle bar reciprocation. 